Ethanol, 2,2,2-Tribromo

In addition to chloroform, many other compounds containing the trichloro-methyl group, CI3C-, show marked physiological action. Thus trichloro-acetaldehyde or chloral hydrate, Cl3C CH(OH) (p. 342), and trichloro-tertiary-butanol or chloretone, CUC CfCHaliOH, are both hypnotics. Similarly, tribromo-ethanol or avertin, BraC-CHjOH, has strong anaesthetic properties. 

Reaction of 1 2 3 tribromo 5 nitrobenzene with sodium ethox in ethanol gave a single product CsHyBrjNOs m quantitative yield Suggest... 

In the 1950 s the US Naval Ordn Lab recognized TATB as a useful heat-resistant expl. Successful small-scale prepn was achieved by saturation of abs ethanol with ammonia and adding 1,3,5 -tribromo-2,4,6-trinitrobenzene. 

Benzene does not react with bromine except with Lewis acid catalysis. Phenols react in a very different manner no Lewis acid is needed, the reaction occurs very rapidly, and the product contains three atoms of bromine in specific positions. All that needs to be done is to add bromine dropwise to a solution of phenol in ethanol. Initially, the yellow colour of the bromine disappears but, if, when the colour just remains, water is added, a white precipitate of 2,4,6-tribromo phenol is formed. 

Note To avoid danger of decompn it is marketed under the name Avertin with Amylene Hydrate (Solution), as Tribromoethanol Solution. Each ml contains 1 g tribromo-ethanol. 

T. Mukaiyama, M. Yamaguchi, and J. Kato, A novel method for the synthesis of 2,2,2-tribromo-ethanols fiom aldehydes and carbon tetrabromide in the presence of stannous fluoride A synthesis of diacetyl-D-erythronolactone, Chem. Lett., 1505 (1981). 

Formals. Paraformaldehyde added at room temp, to a soln. of 2,2,2-tribromo-ethanol in 89.6%-H2SO, and the product isolated after 0.5 hr. -> bis- (2,2,2-tri-bromoethyl) formal. Y 87%. — Acetal formation by the usual methods is difficult to achieve with negatively-subst. alcohols. F. e., also cyclic acetals from negatively-subst. diols, s. K. G. Shipp and M. E. Hill, J. Org. Ghem. 31, 853 (1966). 

---